slack-infra/tempelis - add a presubmit prow job for testing slack config changes

[Priyankasaggu11929]

Describe the issue

At the moment, we only have a post submit template that fails whenever a PR making slack-config changes has broken content or missed adding some part of the configs.

These missing changes should be flagged at the time of PR creation only by the CI jobs.

In the last 6 months to 1 year, we have come across a lot of such instances of similar broken configs.

Existing postsubmit tempelis job is defined here - https://git.k8s.io/test-infra/config/jobs/kubernetes/sig-k8s-infra/trusted/sig-contribex-tempelis.yaml

Looks like tempelis has a --dry-run flag, we can try to set it to true in case of presubmit and start from there.

Also, here’s the tempelis code - https://github.com/kubernetes-sigs/slack-infra/tree/main/tempelis

[Priyankasaggu11929]

/assign @Prajyot-Parab

(from Feb 25, 2026 ContribEx call)

[Priyankasaggu11929]

Recent example of failing Postsubmit Tempelis job are here - https://testgrid.k8s.io/sig-contribex-slack-infra#post-community-tempelis-apply

we would want these post PR merge changes to be flagged in a presubmit job, so, they can be addressed as part of the PR reviews itself.